1. Field of the Invention
The present invention relates to a method of identifying a probe position and a probing method in a prober for a substrate to be examined, e.g., a semiconductor wafer.
2. Description of the Related Art
In the semiconductor device manufacturing process, a large number of semiconductor devices are formed as chips on a semiconductor wafer. Then, the wafer is cut into the chips, i.e., the semiconductor devices in a die cut step. In the semiconductor device manufacturing process, before the wafer is cut, the electrical characteristics of the semi-completed semiconductor devices are tested and determined by using a prober. Only the semiconductor devices that are determined as non-defective articles as the result of test measurement are sent to the subsequent steps, e.g., packaging.
The prober has a wafer work table which is made to be movable in the X, Y, Z, and .theta. directions. A probe card having a large number of probes corresponding to the electrodes pads of a semiconductor device is fixed above the work table with an appropriate holding tool. For measurement, a test target, e.g., a wafer, is placed and held on the work table. The work table is driven, the probes are brought into contact with the electrode pads of the semiconductor device, and test measurement is performed by a tester through the probes.
In order to accurately bring the probes of the prober into electrical contact with the electrode pads of the semiconductor device, the distal ends of the probes must be correctly guided to the electrode pads of the semiconductor device and aligned with them. Conventionally, a specific semiconductor device on the wafer is moved to under the probe card by moving the stage. Then, the distal ends of the probes are recognized by utilizing, e.g., a camera, and manually aligned with the electrode pads of the semiconductor device. In this method, the operator must be specially trained, and the aligning operation becomes very cumbersome. When a probe card, e.g., a probe card having probes of a so-called vertical type, that visually conceals contact between the probes and the electrode pads is used, visual observation for the purpose of alignment is difficult, sometimes making it difficult to perform accurate operation.
A technique of automatical alignment in probers has recently been developed, as disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 61-283138. This technique is based upon a premise that the probes are arranged on a probe card without any error, and the probe card is fixed to a prober correctly. However, it is actually difficult to precisely arrange the probes on the probe card in advance, and differences among probe cards always occur. Even though the probes are arranged on the probe card as previously designed, it is unavoidable to cause some changes by using the probes repeatedly. It is also unavoidable to cause an error in aligning when the probe card itself is attached to the prober.
As the degree of integration of a semiconductor device increases, the number of probes needed to test one semiconductor chip is likely to increase. Recently, a probe card having 1000 to 2000 probes has been required in semiconductor manufacturing processes and, in this case, it is not easy to recognize the distal end of a reference probe of the probes from under the probe card. In a probe card having vertical type probes, when the distal ends of the probes are seen from under the probe card, they are recognized as a set of countless points, and it is not easy to discriminate the reference probe from the others.